1. Field of the Invention
The present invention relates generally to a method and flare burner apparatus for flaring gases, and more particularly, to a method and flare burner apparatus for flaring inert vitiated waste gases whereby such gases are burned in an efficient and stable manner.
2. Description of the Prior Art
Flare burner apparatus are commonly utilized for disposing of waste gases, both continuously and intermittently. Generally, such flare burners include continuously burning pilot flames for igniting and maintaining the burning of the waste gases.
When the flared waste gases contain inerts in high quantities i.e., the waste gases have heating values below about 300 BTU/SCF when burned, problems have been encountered in the use of prior flaring methods and burner apparatus. That is, the burning of such inert vitiated waste gases can be inefficient and/or unstable and in windy environments the flames can be blown out. Examples of particularly difficult inert vitiated waste gases are those containing high concentrations of carbon dioxide such as steel mill blast furnace residue gas and the gases produced in subterranean formation carbon dioxide secondary recovery processes.
Prior to the present invention inert vitiated waste gases have been flared in conventional flare burner apparatus by combining fuel gas with the waste gases to form a relatively high calorific value gas mixture and then conducting the high calorific value gas mixture to the burner apparatus. Because this technique requires high quantities of fuel gas and is expensive to carry out, special flare burner apparatus have been developed which burn a separate stream of a fuel and air mixture at the burner apparatus to heat a portion of the waste gases to the temperature required for ignition and burning thereof. While various forms of this type of flare burner apparatus have been developed and used successfully, they are generally limited in size and capacity because the quantity of the fuel and air mixture which can be economically provided at the flare burner apparatus is limited. That is, the higher the quantity of inert vitiated waste gases to be burned, the more auxiliary fuel and air mixture required and the more expensive the flare burner apparatus.
Other flare burner apparatus developed prior to the present invention for burning inert vitiated waste gases have included means for discharging auxiliary fuel gas into the atmosphere around and/or into the waste gases whereby the fuel gas mixes with atmospheric air, is ignited and burned thereby raising the temperature of a portion of the waste gases to the ignition temperature thereof. While this type of flare burner can be used successfully, the burning of the fuel gas and waste gases using such a burner in a windy environment may sometimes result in an unstable and/or inefficient burning.
A variety of air assisted flare burner apparatus wherein combustion air is forced through or around the burner by one or more air blowers have been developed and used in the flaring of combustible gases. However, such forced draft burners are ineffective for flaring inert vitiated waste gases in that the gases are diluted and cooled by the air and consequently, do not reach the temperature at which ignition will occur. A large capacity air powered smokeless flare of this type is described in U.S. Pat. No. 4,457,696 issued July 3, 1984.
Thus, there is a need for a method and burner apparatus for flaring inert vitiated waste gases whereby the gases can be efficiently burned in a stable manner in windy environments and whereby high flow rates of such waste gases can be flared.